The present invention relates to absorbent articles.
A various assortment of absorbent articles, such as disposable diapers and sanitary napkins, have been proposed for absorbing and retaining body fluids. Such articles have been constructed with an absorbent pad having a relatively large volume of pad material, in order to provide the necessary absorbency and fluid holding capacity for the articles, which adds an undesired bulk to the articles. For example, disposable diapers are commonly made from a fluid impervious backing sheet, a fluid pervious cover sheet, and an absorbent pad, such as comminuted wood pulp known in the art as wood fluff, located between the backing and cover sheets. The pads of such conventional diapers are relatively bulky, resulting in a poor fit and minimal comfort to the infant.
More recently, it has been proposed to include highly absorbent materials, such as hydrocolloid polymers, in the pads. In theory, the hydrocolloid materials permit a reduction in pad bulk while increasing desirable absorbent and fluid holding characteristics of the pads, since such materials are capable of absorbing and retaining many times their weight in liquid, such as urine or other body fluids. In practice, use of such materials in absorbent articles has been limited due to difficulties caused by the nature of the materials.
It has been contemplated that the hydrocolloid materials may be placed in a central region of the articles at a location where body fluids, such as urine, are applied to the articles. However, the hydrocolloid materials swell and become gelatinous when wetted, and it has been found that the wetted materials form a film on the pad which decreases the rate of further fluid penetration into the pad. Thus, although the materials initially absorb the body fluids, they may later cause saturation and back wetting of the fluids in the central fluid receiving region of the articles. Moreover, in general it is desirable to retain the body fluids at a location spaced from the point of application to the articles in order to make maximum use of the pad.